A partial ACL tear is an incomplete tear or injury to the anterior cruciate ligament (ACL).  Partial ACL injuries might be treated differently than a complete tear of the ACL.   Recovery from a partial ACL tear might be faster than the recovery from a full tear, but it is also a much more complicated decision-making and treatment process. There is a number of variables and considerations that require careful attention in determining how we might treat a partial ACL tear.  The goal of the treatment is to minimize the risk of having instability or giving-way episodes.  

ACL serious knee injury
Torn ACL

Why do Partial ACL injuries occur?

Most ACL tears occur from non-contact injuries. When you turn, pivot or twist and you feel a pop or tear inside the knee, then there is a chance you injured your ACL. That injury could be a “partial tear” or a “complete tear” of the ACL.  Injuries to the ACL or Anterior Cruciate Ligament are becoming more and more common.  The ACL is composed of two pieces, or bundles — so it is possible to suffer only a partial ACL tear, as opposed to a complete ACL rupture. 

What is the Anterior Cruciate Ligament (ACL)?

Partial Anterior Cruciate Ligament Tear InjuryThe anterior cruciate ligament  (ACL) is one of the more vital and more easily injured ligaments within our knee. Ligaments are very tough, fibrous tissue structures.  Ligaments hold our bones together and allow us to bend, twist, pivot and rapidly accelerate and decelerate and yet maintain the stability of our joints. The ligaments of our knee hold it together. Most ACL ligament injuries in the knee are non-contact in nature.

Partial ACL Tear
ACL Tear

If you have sustained an injury to your knee during a pivoting, or twisting incident,  you felt a pop and then noted the inability to walk — as well as significant swelling within your knee — there is a significant chance that you have injured your anterior cruciate ligament.

The anterior cruciate ligament or ACL is the most commonly injured of the four major ligaments that exist within our knee. The ACL is a large ligament composed of two “bundles”.  Therefore injuries can lead to a partial (one bundle) ACL tear or a complete ACL tear (both bundles).  A good examination by your doctor can often tell the difference between a partial ACL tear and a complete tear.  Often times, you will be referred for an MRI to confirm the diagnosis.

Complete ACL Tears:

A complete ACL tear involves the complete disruption of all of the ligament tissue that connected both the femur and tibia. You may simply possess discomfort, pain, and swelling – – – or you may perceive that the knee is unstable and feels like your knee wants to buckle or give way. We have covered the treatment of complete ACL tears elsewhere within this website,  and whether or not ACL surgery is necessary as well.  I recently placed two ACL Surgery blog posts on this site. The first will help you determine if ACL Surgery is necessary and what questions you should ask your surgeon.  And a follow-through post of steps you should take before surgery and after surgery to minimize the risks of complications and improve your overall results following an ACL reconstruction. 

Partial ACL Tears

A partial ACL tear involves an injury to only a portion of the ACL. The normal ligament has an Anteromedial bundle and a Posterolateral bundle. A partial injury means that only one of the two bundles was torn.  Therefore, the second bundle is intact. Many patients who sustain a partial ACL tear will be able to return to their prior level of activity without complaints of buckling,  instability or giving way. It may, however, take many months to recover from the injury and to complete the extensive rehabilitation necessary.

Unfortunately, a fair number of you with a partial ACL tear will not be able to return to sports because your knee feels unstable or loose. Therein lies the issue with partial ACL tears … some people with a partial tear will not complain of instability of their knee with sports, but some might.


partial ACL tear Howard Luks Westchester County, NY

What I’m getting at is simply the fact that we should not look at your ACL  tear as being “partial” or “complete”, we look at your KNEE as being “functional” or “non-functional” or “stable” vs. “unstable”. 

If you have a functional and stable partial tear of your ACL, that means that you have torn a certain portion of your ACL fibers, however, you are still able to participate in sports without the feeling of the knee giving way or being unstable. If you possess a nonfunctional partial tear of your ACL, that means that you have torn enough of your ACL fibers that your knee no longer feels stable. That means that you are at risk of further injury if you return to your prior level of sports participation. Every time your knee buckles or gives way you run the risk of tearing other structures within the knee, such as the medial or lateral meniscus. If you sustain tears of either the medial or lateral meniscus, which are the shock absorbers within the knee, then you are at risk of developing osteoarthritis. You, therefore, want to eliminate or minimize the risk of buckling,  instability or giving way and therefore a patient who presents with a partial ACL tear, who complains of instability, will likely present as an appropriate candidate to consider an ACL reconstruction or possibly an ACL augmentation.

ACL Repair and Treatment Options – If Partial ACL tear surgery is necessary

The difference between an ACL reconstruction and an ACL augmentation is fairly simple. During the process of an ACL reconstruction, we will reconstruct or replace the entire ruptured ligament. Anatomically, the ACL is composed of two separate bundles and a complete reconstruction will compensate for both of those bundles. In an ACL augmentation, you have only sustained a partial tear. That means that a portion of your ACL remains intact and should be normal. Many competent sports medicine orthopedic surgeons are capable of reconstructing only the torn portion of the ligament, leaving the normal portion alone. There are many advantages to an ACL partial tear augmentation over a full ACL reconstruction. While the discomfort and the nature of the surgery are virtually identical – – – it is far more likely that someone who undergoes an augmentation will have a much more natural feeling knee when all is said and done. The reason for that is because the normal ACL has certain nerves within it. Those nerve fibers give the brain certain feedback as to the position of the knee joint. It turns out that those nerve fibers are quite important. If we preserve the intact portion of your ACL, then we are preserving those nerve fibers and hopefully preserving the integrity of your knee in the long run.

In some published series, up to 50% of athletes can be expected to return to sports with a partial ACL tear which is treated without surgery. Before returning to sports, an athlete should complete a formal rehabilitation program.  A thorough evaluation by your doctor, physical therapist or athletic trainer should also be performed to make sure that your knee is properly rehabilitated and ready to return to the field.  

Disclaimer:  this information is for your education and should not be considered medical advice regarding diagnosis or treatment recommendations. Some links on this page may be affiliate links. Read the full disclaimer.

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About the author:

Howard J. Luks, MD

Howard J. Luks, MD

A Board Certified Orthopedic Surgeon in Hawthorne, NY. Dr. Howard Luks specializes in the treatment of the shoulder, knee, elbow, and ankle. He has a very "social" patient centric approach and believes that the more you understand about your issue, the more informed your decisions will be. Ultimately your treatments and his recommendations will be based on proper communications, proper understanding, and shared decision-making principles – all geared to improve your quality of life.

25 comments on “Partial Anterior Cruciate Ligament – ACL – Tears

  • Dr. Luks,

    I just received word that I have a partially torn ACL and partially torn meniscus. I am 57 yuears old and the injury was sustatined while I was officiating a high school football game. My doctor has offered two routes: 1. a “clean-up procedure” without ACL reconstruction. I would have to wear knee brace when officiating in the future but without ACL surgery, my ability to cut, move sideways will be limited, or 2. ACL reconstructive surgery and meniscus procedure. This should give me near pre-injury movement and running abilities.

    I’m torn and confused; I would like to officiate 5-8 additional years. I do have a CD copy of the MRI and the x-rays were negative regarding fractures. Thank you. Excellent website and very informative!

    • Joe…
      I’m left wondering why one of the options discussed wasn’t physical therapy? Many people with partial ACL tears have a functional ligament and no instability. A few people will have instability with a partial tear and then a decision can be made with regards to bracing or surgery. Undergoing an ACL recon at 57 is not going to be a simple straightforward process. Also, keep in mind.. Many active 50 somethings have meniscus tears and do not even know it. Not all meniscal tears require surgery.. Even in active individuals.

      Let me know how the PT works for you.
      Howard Luks

  • Dr. Luks

    I’m a 28yr old male that was diagnosed with a partial ACL tear in my right knee. I am still very active lifting weights, playing softball, and basketball on a weekly basis. I’ve been living with it for 4 years. Since the incident “basketball” I’m not nearly as strong lifting or explosive jumping and running and my knee feels tight and weak for days after heavy sports or leg workouts, although it doesn’t buckle. What would be your thoughts on my situation?



    • Adam.. A thorough exam and further discussion is necessary. Instability comes in different “flavors”. Some people will have significant instability where the knee buckles and you fall or it can be more subtle. After a discussion and an exam you and your surgeon can determine if therapy, or surgery is potentially in your best interest.

      Good Luck
      Howard Luks

  • Doc Luks,,

    i am only 17 years old and in this April 21 2014 it will be 4 years after my ligament tear , I had a very bad time , I seen more than 17 doc. half of them said a surgery is important and some said it will be better if I am having my surgery after am an adult , so that the growth may be complete. ……even though there were times not even my pain killers couldn’t help me…..now I think it has been 4 months I am feeling much more less pain , and am getting good exercise ….and I can walk with out using any aids …and I am in a doubt that had the ligament tear completely cured…I had been googleing it for some time to know a better result, until I find you,….I seen some results like people talking like the muscle must had grown and such kind of things……doc,” I need to know if I take a MRI scan , is there a chance to show the fully grown ligament, or a cured ligament”……instead of showing the tear and the muscle grown in between them…..I will die to know it from you….because I had seen the surgery in youtube and am seriously very scared…….my presen situation is : much more better in walking , feeling a little more strong leg and tiny curve back words when I normally stand ,but no pain.

    • Jerry… At 17, if ACL surgery was needed, it is safe to proceed from a growth perspective. The ACL ligament does not heal, and muscle does not grow inside the knee to fill the gap after an ACL tear. IF your knee is unstable it is time to sit down once again with a sports medicine doc and talk about your options. Another MRI might shed some light on the situation and let you know if anything else has been injured too.

      No one can force you to have surgery… if it scares you, you might not be ready… or you might simply need to find a doc you are more comfortable with ?????

      Good Luck
      Howard Luks

  • i am 34 and I compete in mixed martial arts. I work fulltime as a nurse. I have a partial tear in acl and mcl from jiu jitsu practice in oct. Im 12 weeks out and still cannot fully straighten my leg and I cannot bring foot to butt. My dr keeps telling me to rest it. Its been 3 months. Im way to active and competitive to continue to sit around and “rest”. I live in georgia. Any thoughts?

    • Rachael.. sorry. Combined injuries to the ACL and MCL can hurt quite a bit. MCL injuries in particular are well known for causing a prolonged recovery process as you are experiencing. While I can not comment on your case in particular, at this point an MCL partial injury should be healed enough to allow for physical therapy to assist in gaining back the range of motion.

      If your knee feels unstable, that is something that needs to be addressed with your surgeon. Multi-ligament injuries are notorious for producing very sore, unstable knees.

      Good Luck
      Howard Luks, MD

  • Dr. Luks,

    Back in late November I fell while skiing and hurt my knee. At the time, I was across the country and unable to get an MRI because of insurance reasons. My knee was very swollen, but the pain was not bad at all. About a week after the incident, I returned to the gym and was able to exercise without any serious discomfort in my knee. Eventually I was able to walk without any limping and it seemed like it was going to heal on its own. When I returned home a week ago (about a month after the injury occurred) I got an MRI and the results showed that my ACL is torn at the femoral end and I have moderate bone bruising. I have not consulted with an orthopedic yet, but I do have an appointment in about a week. My question to you is do you think it would be possible to return to my normal, very active lifestyle (mainly skiing and running) without having surgery?


    • That’s a great question Sudie. Unfortunately I can not answer it for you :-(. There are some people who get by without an ACL, but they generally do not participate in aggressive sports such as skiing. Ms Vonn can attest to the fact that it is very hard to ski without an ACL.

      Good Luck with your meeting with your Orthopedist.
      Howard Luks

  • Dear Doctor Luks,
    I am 44 years old from Galle Sri Lanka. I play badminton since the age of 8 for my school , university and the club.In 2012 August I had left knee injury- lateral collateral ligament tear at its insertion to the femoral condyle, anterior cruciate ligament tear (Report has not mentioned whether it is a 100% tear or not) and tears in of posterior horns of both menisci and meniscal cyst in relation to lateral condyle (M.R.I report- 2013/11- got late due to technical reason) while playing badminton.I had pain, mild swelling and restricted movements initially but with physiotherapy and anti inflammatory drugs now I can walk fast and climb stairs (with mild weakness) without pain and discomfort . I notice some muscle wasting in my left thigh. I did not attempt running or playing badminton, but now I enjoy swimming without painful knees.I do not intend to play badminton.
    Can you please tell me , Dr Luks
    1. the suitable mode of treatment considering the future course of my life.
    2. I f it is not reconstruction of A.C.L. what is the likelyhood of osteoarthitis in my knee.
    3.the sport activities and exercises suitable for me to avoid muscle wasting further and keep me fit.

    • With a multi-ligament injury – the ACL and LCL – you are at very high risk of having significant instability and giving way. If that happens then you can suffer other injuries such as meniscus tears or damage to the cartilage.
      Unfortunately with a multi-ligament injury and a meniscus tear, you are at an elevated risk for developing arthritis. Weight training under supervision in a gym would likely be well tolerated. But any sports would be not be advisable given the unstable nature of your knee.

      Good Luck
      Howard Luks

  • Dear dr.lucks
    i fell on my leg while playing soccer 3weeks ago. My i have a partial acl tear. Doctor took away my meniscus. Since the operation i have been takin phsical treatment everday. Now my knee stabilty is getting well gradually and i can walk. What should i do to recover fullly. İ afraid of using my leg in case i can hurt my acl totally. İs it possible to tear it totally while trying to streghten my leg and what exercises should i do to streghten my leg.need your help, thank in advance

  • Hello, I am 18 years old and I was playing basketball and when I jumped up for the rebound I felt shakingon my knee than I went to the ground and was unable to stretch my leg. After 20 seconds I slowly stretched it out and it felt like something poped into place. I did not hear a pop though. Its been a month exactly that I have had this injury. I went to an orthopedic doctor a few days ago and got my MRI done and I woll find out exactly what I have in 1 week. My orthopedic doctor thinks it may be a parcial acl teae after some movements with my leg. I have been able to walk fine with and without a brace. However , yesterday while walking I was not paying attention and my leg locked and leaned back and I got pain for about 30 seconds. I dont mot feel pain though on the acl. My injury is on my left leg and on the left side of my knee. I truly hope I didnt do more damage to any of the ligaments and am placing ice on it every day to ensure I do not injure it. My legs do not lock up. I dont even feel pain when I walk. The only time I ever feel pain is if my leg straightens and I put weight when it leans back. Please respond. Im a kid whos freaking out that he may never be able to play basketball again. What do you think it might be? And what type of surgury would you recommend? Iv been told of many types of way but is it really good to take a piece of your hamstring out to heal your ACL? I would love some feedback. Thankyou

    • David.. I’m sorry that I’m not going to be able to be of great assistance to you tonight. Too little information.. and I can’t offer treatment recommendations to people online who are not patients of mine. Given the injury that you note, it MIGHT not be an ACL issue, but MIGHT be a bucket handle meniscus tear. That would explain the locking you experienced. Time will tell young man… let’s see what the MRI shows. Feel free to come back after you have some more information. Please understand that this is for informational purposes only.. it is not meant as a diagnosis or treatment recommendation. To avoid further injury you can talk to your surgeon about whether or not crutches would be useful to prevent further injury, until you know the results and have a plan in place.
      Good Luck
      Howard Luks

  • I do apoligize for the questions. I didnt notice until I reached the bottom of the page, thankyou for the input though! The doctor however told me not to use crutches. He didnt really get much into detail. But I figure he knows best.

  • Hi doc I’m 18 yrs old , exactly three and half months ago my knee got hurted as the result of playing football. On the spot I went to doctor and he said you should do an MRI to clarification of the issue. After that I did MRI and the result shown as an impression: 1- Mild effusion, suprapatellar bursa 2- Early onset Grade-I meniscal changes, posterior horn of medial meniscus. When I did MRI, the result did not show that the ligament is hurted, but it was. By considering the above results, the doctors said that you should be operated and I did accept it. The doctor said after 15 days you will be absolutely fine, but: v After operation (one and half month) I felt that my knee has not become fully fine yet. And I went again to doctor and he said you need to do MRI once again to have a better understanding and I did. And this time, the result shown ACL partial tear.
    The doctor said don’t go for operation and do the exercises but I’m disturbed alot so what’s your opinion.
    Can I do the operation ?
    I want to be absolutely fine as soon as possible it is.

    • I’m sorry Sohail .. I can not make specific recommendations to people who are not my patients.
      Good luck to you.

  • Hello i am a 15 year old male, i had an ACL operation and it was successful. After 3 and a half months i tore my acl again should i do the operation? i play in a professional soccer team.

    • How did you re-tear it? Did you go back to sports after only 3 months ?? What graft was used?

      If you felt like you needed the first ACL reconstruction, why would that change after a second tear? It is unlikely that a teenager could return to professional level sports without a functioning ACL.

      Good Luck
      Howard Luks

  • Hi Dr. Luks,

    I am 25 years old from Jakarta, Indonesia. I am so glad that I found your article in this website. Well, first I’ll tell my diagnosis story on my Right Knee injury. I currently living in Guangzhou, China. I am a very active person in martial arts, fitness & other sports. 5 months ago I injured my ACL & some part in the Meniscus because of the jiujitsu training. At first, I checked with the 2 Chinese orthopedics back when I got my injury, at first the doctor didn’t give any further physical exam, & ask the MRI for further diagnosis – yet, both of the doctor didn’t do the physical exam on my knee – suggesting to wear leg brace (not knee brace – if you know what I mean). All they do is based on the MRI results, which I believed what they diagnosed that, I had complete torn on my ACL & suggested to do the surgery. Well, in that time they didn’t suggest to do it directly, because I still had my swelling in the knee. After 3 weeks I had a chance to go back to Jakarta, & then I immediately went to my trusted orthopedic, and yes he did the physical exam with the McMurray test, & diagnosed me with a partially torn after the exam (found the stiffness in the muscle on that time). More, he gave me the injections of “calcitonin” like 3 times a week without any charges (he’s a social doctor too FYI), yet he saw my MRI result, but what he commented on the result is that he couldn’t just believe what MRI report told, he needs to do the physical exam more. Right now, i am able to walk normally, bending, and putting the heel into my butt, however then I checked again with another Indonesian doctor and he diagnosed that its a complete torn & need surgery, without doing any physical exam too (as like the Chinese). Well, i still got lots of chances to saw my trusted orthopedic more often & he still did more physical tests during the i always visited him. He suggested to always wear the knee brace until it naturally healed & restored (it might not be 100% restored he said, but its better than the surgery) – the process might take 6-9 months he said.

    But still I’ve complaints – I still have pain sometimes when I tried to even jogging, walk on the stairs, & felt unstable sometimes (not everytime). I still wear my knee brace & try to come back to train again in jiujitsu, but again some twisting movement or more active movements I didn’t do it, but since I can feel the pain during I actively move/run – I rest to train jiujitsu, let it be restored completely, and waiting.

    So, right now I am still confuse whether I need the surgery or not.
    What is your thoughts for me, if you were me? Hoping that you can suggest some more details information too.

    Thank you.

      • Hi Dr. Luks,

        The MRI reading was a translation like this;
        “Result of right knee MRI plain scan
        1. The ACL was completely torn. The PCL, MCL & LCL were partially torn. Anterior angle of meniscus was torn.
        2. Internal condyle, lateral condyle of right femur & lateral tibial plateau were focal bone marrow edema.
        3. The right knee was hydrops articuli.”

        These are all I got – but what the physical exam result was completely different.

        However, I am still confuse now.

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